1. Field of Invention
The proposed invention relates generally to hand controllers or computer display pointing devices such as mouses, joysticks, and trackballs. More specifically, it relates to ergonomically shaped pointing devices, which eliminate harmful stresses in wrist and hand joints thus providing substantially improved functionality and prevent computer related injuries.
2. Description of Prior Art
The use of pointing devices for entering signals into a computer is well known in the art. Moreover, there is a great variety of so-called ergonomically shaped devices for this purpose. The most widely known devices can be represented by examples. U.S. Pat. No. 3,835,464 to Rider (1974) discloses a hand-operated position indicator for computer controlled display system. A hemispherical housing provides a plurality of buttons and a sphere located on a bottom structure supported on the underlying structure.
Basic functions of different mouses are very similar and remain about the same for a long time. Some common problems in the use of mouses are well known in the art. After a protracted period of continuous use, there is a muscle fatigue in a forearm, soreness, and even pain in the hand. In recent years, a medical problem formerly described as wrist level median nerve entrapment, but now commonly referred to as carpal tunnel syndrome (CTS) has taken on an ever-increasing significance, particularly in monetary payoffs by states for worker""s compensation claims and by insurance companies for claims related to CTS surgery. The decease usually can not be treated well without a complete stop of use of the injured hand. By a definition of the American National Institute of Health xe2x80x9cCTS occurs when tendons in the wrist become inflamed after being aggravated. A tunnel of bones and ligaments in the wrist narrows, pinching nerves that reach the fingers. Symptoms range from a burning, tingling numbness in the fingers, especially the thumb and the fore-and middle fingers, to difficulty gripping or making a fist. Approximately one percent of individuals with carpal tunnel syndrome develops permanent injury. The majority recover completely and can avoid re-injury by changing the way they do repetitive movements, the frequency with which they do the movements, and the amount of time they rest between periods when they perform the movements.xe2x80x9d
It is commonly believed that the cause of the decease is in that those pointing devices are not well shaped ergonomically to fit to the use""s hand. Two common directions of improvements can be specified:
better accommodate pointing devices to the anatomical shape of a relaxed hand posture and to decrease bending of the forearm-wrist joint;
decrease a probability of inadvertent activation (pushing, clicking) of the control keys generating computer commands.
There are many patents issued for ergonomically shaped pointing devices improving their shape in a number of ways. U.S. Pat. No. 4,862,165 to Gart (1989) proposes an anatomical shape to fit the hand perfectly in order to avoid hand fatigue and discomfort after even a protracted period of use. This mouse is shaped so as to support the elevated palming position, support a thumb, support middle, ring, and small fingers in a relaxed wrapped position. However, the main operating forefinger is in a stretched and consequently stressed position above the push button. The user""s forefinger can not relax unattended to avoid activation of a button. This is the main reason of static stress, because this mouse has no protection from unintentional activation.
U.S. Pat. No. 5,576,733 to Lo (1996) teaches that a conventional mouse requires constant muscular force to be applied to the hand, wrist, and forearm to maintain their positions twisted from neutral posture. For a three-button mouse, the fore-, middle, and ring fingers must be kept in constant tension to prevent them from resting too heavily on the buttons and depressing them inadvertently. Lo teaches that the hand is about 80-90 degree twisted left from the normal upright position with a conventional mouse. Lo supposes that the best-relaxed position of the hand on the pointing device must be vertical upright keeping the fingers in a stack position to eliminate twisting of the hand.
However, the fingers controlling the buttons are all straightened, hence, contradicting the idea of the wrapped fingers typical for a relaxed hand. Moreover, the vertical upright position is optimal for only a hand, which elbow is very close to the user""s body. It is not so relaxed, when the elbow is distant from the body as in a usual situation, when the computer keyboard is in front of a user. It is easy to understand imaging a pistol grip in hand: when the elbow is squeezed to the body, then the grip is about vertical. When the elbow moved away from the body, the grip becomes substantially horizontal. Consequently, the hand on a mouse must not be turned upright too much to be vertical: it is not anatomical and, hence, limits the hand functionality. It is especially true, when the hand is operating a mouse at the desktop edge. Besides, this mouse substantially limits finger functionality.
U.S. Pat. No. 5,355,147 to Lear (1994) proposes a vertical mouse structure with a palm-wrist support. The activator switches or push-buttons are designed to be pressed by the thumb and the bent fingers wrapping a vertical grip. This mouse provides as good functionality for the fingers as any other pointing device of the type known as joystick. It is also protected from unintentional button activation in the same way as other joystick-type pointing devices. However, this device is cumbersome in comparison with conventional mouses and does not provide a possibility of using the wrist and finger functionality for fine positioning. Besides, it is rather difficult for computer users to change usual function of the middle finger to the thumb.
One more example is a well-known highly operable pistol grip. It provides at least two important functions simultaneously: a firm grip and a gentle relaxed position for the operating forefinger pulling a trigger. Pistol grips are very functional in both senses. Such grips used to be optimal for vertical controllers. They are widely used as vertical joystick devices. Such kind of grips is substantially protected from unintentional activation. In a vertical grip, the axis of rotation/bending of the forefinger is vertical. The finger can be kept standby in this position as long as needed without any power applied. Hence, there is no specific stress in the hand, which is typical for all horizontally operating mouses.
U.S. Pat. No. 5,296,871 to Paley (1994) claims a three-dimensional mouse operating in free space. This pointing device is designed essentially as a pistol grip including a thumb push button, a forefinger push button, and a grip push button. Paley has mentioned that such grips are substantially free from a danger of unintentional activation. Consequently, they can be recognized as safe grips: they don""t induce the static tension in a hand and a stress in the user""s brain from the necessity to continuously control the command fingers. On the other hand, these grips are safe, because they are essentially protected from generating erroneous command. That is why such grips are widely used in mission critical applications including weapon control. However, they need some constant efforts to just be held in hands.
Unfortunately, pointing devices of this kind is difficult to use on a desktop surface in comparison with conventional mouses. That is why the ergonomic mouse by Gart is not safe and has the same drawback as other conventional mouses. It was shaped essentially similar in some respect to an orthopedic pistol grip and adapted for use on a horizontal surface. That is the operating forefinger pulling the pistol trigger bends in horizontal but not in vertical plane. While it is in relaxed position in a pistol grip, it can not be relaxed with such grip in horizontal position to avoid an inadvertent action onto the underlying push button actuators. The axis of rotation is changed from vertical to horizontal, hence, the finger is affected by its own weight. It must be supported by a price of constant tension and compressed wrist joint. The static tension in operating fingers and, consequently, in the hand and wrist joint and forearm muscles is the main problem of all currently used horizontal pointing devices including trackballs. Namely this unnatural tension produces hard pain in the hand and limits functionality of all mouses and trackballs. This problem is a main source of injuries generated by pointing devices operating on a horizontal surface.
The most recent patents on pointing devices repeat similar idea about further improvement of the shape of pointing devices not modifying substantially their functionality. Hence, the harmful tension persists in the user""s hand. More and more users become the victims of computer generated injuries. Similar future can be predicted for their children, unless a safe horizontal pointing device will be produced.
U.S. Pat. No. 5,726,683 to Goldstein (1998) claims an ergonomic computer mouse keeping the hand slightly elevated and upright. These ideas yet not combined have been described in U.S. Pat. No. 5,581,277 to Tajiri (1996) with elevated palm support, and in U.S. Pat. No. 5,576,733 to Lo (1996) with the upright mouse. The most cited patent to Gart also describes substantially elevated shape of the pointing device. The slope of the push-button surface of the pointing device by Goldstein is increased from usual 0-20 degree up to about 30-40 degree in average relative to a horizon. However, the slope of the buttons is yet essentially horizontal in average. The projection of the front push buttons (front actuators) on a horizontal plane is bigger then on a vertical plane. It is still very similar to the slope of conventional mouses and, hence, very close to them in fimctionality (for example, the MK mouse produced some years ago by WACHI Electronics Co. for NEC computers, Japan). The critical threshold of the downward force capable to click the button is determined by a minimurn, not maximum or average, slope of the front button. Indeed, any buttons having a substantially horizontal portion are not protected from inadvertent activation by a heavily loaded hand and fingers. Hence, this mouse is not safe, because the user must be in constant stress to avoid inadvertent button activation by the unattended hand.
The mouse designed by Goldstein has a special side support for the forefinger. The support is made nearby the button. The finger can be moved there to rest between clicking operations. Then it must be repositioned to the button in order to perform another click. Obviously, such repositioning is not of practical use during continuous operation. It damages the overall functionality. The authors of that patent were certainly aware of the problem of constant tension caused by the stressed forefinger, but failed to solve it. Even mouses with essentially elevated top surface, like those patented by Gart, by Goldstein, or the MK mouse by WACHI Electronics, do not free a hand from the stress generated in a wrist by the constant danger of unintentional activation.
Some non-patented pointing devices of original design can be found in the computer market. They are not protected from unintentional activation of the switching buttons. Consequently, all users are brought into continuous stress and especially those, who work with large spreadsheets, office, CAD and drawing software, dynamic games etc. The higher a psychological risk of inadvertent clicking of the actuators, the stronger is the wrist stressed. This constant stress inevitably affects user""s central nervous system and a very fragile carpal tunnel protecting the nerves controlling the hand and fingers. This protracted non-anatomical effort, keeping the fingers away from the switching buttons, injures the wrist carpals. At the final stage, any user is at high risk of organic transformations in the wrist and chronic musculoskeletal diseases.
The above mentioned examples show that the prior art patents are concentrated basically on a static position of the hand and fingers. Many of previous art mouses, for example the one designed by Gart, fit a hand very well. An average user with a healthy hand and wrist joint can hardly distinguish between unsafe and safer mouses not having used them long enough. Any attempt to compare the functionality of different mouses by measuring electric potentials on the hand muscles (U.S. Pat. No. 5,726,683) without well-approved dynamic medical schemes and reasonable statistics is doubtful.
In order to summarize main drawbacks of the previous art and come to conclusion, we shall consider some basic principles of anatomical functions of a human hand, which can show a way to the right functionality.
Many mechanical medical devices for treatment of the carpal tunnel syndrome are patented. These devices are designed for healing an injured wrist by means of stretching it in a direction away from the elbow and are described in the U.S. Pat. No. 5,653,678 (1997) and U.S. Pat. No. 5,707,345 (1998) to Fulk, U.S. Pat. No. 5,466,215 to Lair (1995), U.S. Pat. No. 5,214,799 to Fabry (1993) etc.
Tendons connected to forearm muscles control a hand and fingers. The strongest muscles of the forearm, called flexors, bend the fingers into a wrapped position or a fist. This is the strongest and safe hand position for powerful actions. Since all tendons pulling the fingers go across the wrist, they inevitably compress the wrist joint. Hence, the carpals come into heavily loaded contacts. However, it is not dangerous. These contacts are naturally protected by thick cartilage tissues and designed for periodic heavy loads and intensive use. The stretching of joints is useful and healing, while their compressing, even being anatomical, can be harmful depending on the magnitude of the pressure and its duration.
When the job is finished, the initially stressed flexor muscles relax. Then different essentially weaker muscles of the forearm, called extensors, pull opposite tendons of the fingers in order to open the fist and prepare it for the next catch-and-keep job. There is no other job supposed to be for such unbending tendons except of short-time weakly loaded moves. Everybody knows, for example, how difficult it is to keep arms up for even a minute. It is anatomically unnatural, and therefore, stressful position. The same is correct about the hand and fingers. Any long time not supported posture keeping fingers over a horizontal plane even a little bit unbent outwardly is harmful. Watching users"" hands operating mouses, one can distinguish that the fore- and middle fingers are usually a little bit up above the sensitive actuators, especially when mission critical operations are running.
Consequently, previous art mouses were designed to be ergonomic for the short moments of clicking actions. However, they all are not ergonomic and even dangerous (unsafe) for the longest rest periods occupying more than about 90 percents of the total operating time, when the hand is resting on the mouse in a stressed position to avoid unintentional activation. These protracted periods of stressful anatomically unnatural position of the user""s hand is still a major problem of the prior art.
This is a paradox, but in fact the user""s hand becomes tired and even injured not from the active job, but due to the protracted unnatural and stressful xe2x80x9crestxe2x80x9d. This problem well recognized in the present invention shows itself the only way to cardinally improve pointing devices. It is, therefore, necessary to exclude a possibility of inadvertent activation of the push-buttons by a relaxed user""s hand. Only in such case, the wrist joint can be at real safe rest between the clicking operations, and the user will be free from specific tensions and stresses, and consequently, from the hand injuries and pain.
Accordingly, the main objects of the present invention are:
(a) to provide safe pointing devices protected from unintentional activation by a relaxed user""s hand;
(b) to provide a pointing device on which a relaxed user""s hand enjoys full rest all the time between the moments of activation of switch buttons being in a highly operable position;
(c) to provide a pointing device with essentially improved functionality for a protracted period of continuous use;
(d) to provide a pointing device, which can be grasped by a hand with all the fingers bent and wrapped into a highly operable and comfortable posture;
(e) to provide a pointing device, where the command fingers can fine touch the command keys and be ready for immediate action without a risk of unintentional activation;
(f) to provide a pointing device gently stretching a hand wrist when a user""s hand is relaxed thus protecting the wrist joint from being strained, aggravated, and injured;
(g) to provide a pointing device, which is functional in a range of conditions: on a wide desktop surface or at the very edge of the desk;
(h) to provide a handy and safe pointing device having additional functionality for scrolling, cursor positioning, menu activation, etc.
(i) to provide safe pointing device adopting any comfortable hand supporting housing by the use of actuators for unbending finger actions;
(i) to provide convenient and safe pointing devices for disabled persons.